Engine device

ABSTRACT

An engine device having a flywheel housing in which a flywheel that is rotated integrally with a crankshaft is accommodated on one side portion of a cylinder block, in which the cylinder block is integrally formed with housing bracket portions each protruding in a direction away from the crankshaft from each of opposite side portions of the cylinder block extending along a crankshaft axial direction, the housing bracket portions protruding from end portions of the opposite side portions close to the one side portion, and a space surrounded by the one side portion, the housing bracket portions, and the flywheel housing constitutes a gear case for accommodating therein a gear train.

CROSS REFERENCE

This is a continuation of U.S. application Ser. No. 16/089,205 filedSep. 27, 2018, which is a US national stage application under 35 U.S.C.§ 371 of International Application No. PCT/JP2017/010038, filed Mar. 13,2017, which claims foreign priority of Japanese Patent Application No.2016-066825 filed Mar. 29, 2016, all the disclosures of which are herebyincorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to an engine device, and in particular,relates to an engine device having a flywheel housing in which aflywheel that is rotated integrally with a crankshaft is accommodated onone side portion of a cylinder block.

BACKGROUND ART

An engine device in which a flywheel that is rotated integrally with acrankshaft is disposed on one side of a cylinder block is well known(see, for example, Patent Literature 1 (PTL 1)). On one side of thecylinder block, a flywheel housing accommodating the flywheel isarranged. Further, on the other end of the cylinder block facing the oneend, a gear case accommodating therein a timing gear train including acrank gear, an idling gear, a camshaft gear, a fuel feed pump gear, andthe like is arranged.

CITATION LIST Patent Literature

-   PTL 1: Japanese Patent Application Laid-Open No. 2012-189027-   PTL 2: Japanese Patent Application Laid-Open No. 2010-261322

SUMMARY OF INVENTION Technical Problem

In a structure where a flywheel and a gear train are arranged so as tointerpose therebetween a cylinder block, there is a problem of twisttaking place in the crankshaft, because a position where the flywheelwith a great moment of inertia is fixed is distanced from a positionwhere a crank gear for rotating the gear train which drives a valvegear, auxiliary machine, and the like, is fixed. The twist in thecrankshaft is one of causes that increases torsional vibration of thecrankshaft, which leads to an increase in the engine noise level.

In view of the problem, an object of the present invention is to reducethe twist in—the crankshaft.

Solution to Problem

An engine device according to an aspect of the present invention is anengine device having a flywheel housing in which a flywheel that isrotated integrally with a crankshaft is accommodated on one side portionof a cylinder block, in which the cylinder block is integrally formedwith housing bracket portions each protruding in a direction away fromthe crankshaft from each of opposite side portions of the cylinder blockextending along a crankshaft axial direction, the housing bracketportions protruding from end portions of the opposite side portionsclose to the one side portion, and a space surrounded by the one sideportion, the housing bracket portions, and the flywheel housingconstitutes a gear case for accommodating therein a gear train.

The engine device of the above aspect of the present invention may besuch that, for example, a weight-reduction space continuous to the gearcase is formed between a cylindrical circumferential wall surfaceportion surrounding an outer circumference side of the flywheel and anouter wall portion covering the outer circumference side of thecircumferential wall surface portion, and a rib coupling thecircumferential wall surface portion with the outer wall portion isformed, in the flywheel housing.

Further, the circumferential wall surface portion may be in a shape of asubstantially truncated cone with its radius decreasing towards thecylinder block, and a surface of the rib on a side of a cylinder headcoupling surface of the cylinder block may be formed to incline so as tobe in a position closer to the cylinder head coupling surface with anincrease in the distance from the cylinder block.

Further, the engine device of the above aspect of the present inventionmay be such that, for example, the gear train includes: a crank gearfixed to the crankshaft; an idling gear meshed with the crank gear; acam gear fixed to a camshaft and meshed with the idling gear; and a pumpgear fixed to a pump shaft of a fuel feed pump and meshed with theidling gear, the flywheel housing has an attaching part for a crankrotation angle detector configured to detect a rotation angle of thecrankshaft and an attaching part for a rotation shaft rotation angledetector configured to detect a rotation angle of the cam gear or thepump gear.

Further, for example, a lubricating oil supply port penetratingly openedin the flywheel housing may be configured so that a meshing position ofthe fuel feed pump gear and the idling gear is visually observable.

Further, for example, the lubricating oil supply port may be such thatan opening area of an internal side of the flywheel housing is greaterthan an opening area of an external side of the flywheel housing.

Advantageous Effects of Invention

In the engine device of the above aspect of the present invention,housing bracket portions each protruding in a direction away from thecrankshaft are integrally formed with the cylinder block at end portionson the flywheel-arranged side of opposite side portions of the cylinderblock along the crankshaft axial direction, and a space surrounded bythe one side portion, the housing bracket portions, and the flywheelhousing constitutes a gear case for accommodating therein a gear train.Thus, the flywheel and the gear train can be arranged on the same endportion of the crankshaft. Twist of the crankshaft can be reduced bysolving the twist of crankshaft caused by the structure having theflywheel and the gear train arranged across from each other over thecylinder block. Further, torsional vibration of the crankshaft whichcauses vibration and noise of the gear train is smaller in a portion ofthe crankshaft closer to the flywheel with a large moment of inertia ascompared to a portion of the crankshaft far from the flywheel. Thus, byarranging the flywheel and the gear train on the same end portion of thecrankshaft, vibration and noise of the gear train can be reduced.Further, by forming the gear case with the cylinder block and theflywheel housing, the number of parts can be reduced as compared to acase of using a separate part for the gear case. Hence, reduction of themanufacturing costs and assembling processes can be achieved.

In the engine device of the above aspect of the present invention, aweight-reduction space continuous to the gear case is formed between acylindrical circumferential wall surface portion surrounding an outercircumference side of the flywheel and an outer wall portion coveringthe outer circumference side of the circumferential wall surfaceportion, and a rib coupling the circumferential wall surface portionwith the outer wall portion is formed, inside the flywheel housing. Thisway, strength can be achieved by the rib, while the weight of theflywheel housing can be reduced by the weight-reduction space. Thus,problems such as an increase in weight, manufacturing defects duringcasting, cracks due to concentration of stress taking place when thethickness of a wall is increased to achieve the strength of the flywheelhousing can be avoided.

Further, by forming the circumferential wall surface portion in a shapeof a substantially truncated cone with its radius decreasing towards thecylinder block, and by forming a surface of the rib on a side of acylinder head coupling surface of the cylinder block to incline so as tobe in a position closer to the cylinder head coupling surface with anincrease in the distance from the cylinder block, accumulation oflubricating oil in the flywheel housing can be prevented, and anaccurate amount of lubricating oil in the engine can be observed.

Further, in the engine device of the above aspect of the presentinvention, the gear train includes: a crank gear fixed to thecrankshaft; an idling gear meshed with the crank gear; a cam gear fixedto a camshaft and meshed with the idling gear; and a pump gear fixed toa pump shaft of a fuel feed pump and meshed with the idling gear, theflywheel housing has an attaching part for a crank rotation angledetector configured to detect a rotation angle of the crankshaft and anattaching part for a rotation shaft rotation angle detector configuredto detect a rotation angle of the cam gear or the pump gear. With this,two rotation angle detectors can be attached to a single part, that is,the flywheel housing. Therefore, an attachment error caused byunevenness in the manufacturing accuracy and the assembling accuracy,which takes place at a time of attaching the two rotation angledetectors to separate parts, can be eliminated.

Further, by configuring a lubricating oil supply port penetratinglyopened in the flywheel housing so that a meshing position of the fuelfeed pump gear and the idling gear is visually observable, the timingmarks on the fuel feed pump gear and the idling gear to be adjusted withthe phase of the crankshaft can be observed through the lubricating oilsupply port. With this, the fuel feed pump can be replaced, adjustingthe timing marks, without detaching the flywheel and the flywheelhousing which are very heavy parts. The number of parts to be replacedand the number of processes for attaching and detaching the enginedevice can be reduced, and the service performance can be significantlyimproved. Further, since the flywheel which is a rotating member doesnot have to be detached, the product safety after the maintenance can beimproved. Further, since an audit window exclusively for mark adjustmentdoes not have to be provided in the flywheel housing, an opening portionarea of the flywheel housing including the gear case can be reduced.Therefore, gear noise leaking to the outside the engine can besuppressed.

Further, by forming the lubricating oil supply port such that an openingarea of an internal side of the flywheel housing is greater than anopening area of an external side of the flywheel housing, the field ofview for visually observing the inside of the gear case through thelubricating oil supply port can be broadened, thus improving theconvenience in the work of adjusting the mark at the time of replacingthe fuel feed pump. Further, with the opening area of the internal sidebeing greater than the opening area of the external side, spilling oflubricating oil at a time of supplying the lubricating oil through thelubricating oil supply port can be prevented.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 A front view of an engine.

FIG. 2 A rear view of the engine.

FIG. 3 A left side view of the engine.

FIG. 4 A right side view of the engine.

FIG. 5 A top plan view of the engine.

FIG. 6 A bottom plan view of the engine.

FIG. 7 A perspective view of the engine as viewed from diagonally front.

FIG. 8 A perspective view of the engine as viewed from diagonally rear.

FIG. 9 A top plan view showing a cylinder block and a flywheel housing.

FIG. 10 A left side view showing the cylinder block and the flywheelhousing.

FIG. 11 A right side view showing the cylinder block and the flywheelhousing.

FIG. 12 A front view showing a gear train.

FIG. 13 A cross-sectional view taken alone the line 13-13 in FIG. 9

FIG. 14 A cross-sectional view taken along the line 14-14 in FIG. 9 .

FIG. 15 A perspective view showing a position where a fuel feed pump isattached.

FIG. 16 A plan view showing the flywheel housing.

FIG. 17 A perspective view showing the inside of the flywheel housing.

FIG. 18 A cross-sectional view taken along the line 18-18 in FIG. 16 .

FIG. 19 A cross-sectional view taken along the line 19-19 in FIG. 16 .

FIG. 20 A cross-sectional view taken along the line 20-20 in FIG. 16

FIG. 21 A left side view showing the flywheel housing and a rotationangle sensor.

FIG. 22 A perspective view showing a lubricating oil supply port,enlarged.

DESCRIPTION OF EMBODIMENTS

In the following, an embodiment of the present invention will bedescribed with reference to the drawings. First, referring to FIG. 1 toFIG. 8 , an overall structure of a diesel engine (engine device) 1 willbe described. In the descriptions below, opposite side portions parallelto a crankshaft 5 (side portions on opposite sides relative to thecrankshaft 5) will be defined as left and right, a side where a flywheelhousing 7 is disposed will be defined as front, and a side where acooling fan 9 is disposed will be defined as rear. For convenience,these are used as a benchmark for a positional relationship of left,right, front, rear, up, and down in the diesel engine 1.

As shown in FIG. 1 to FIG. 8 , an intake manifold 3 and an exhaustmanifold 4 are disposed in one side portion and the other side portionof the diesel engine 1 parallel to the crankshaft 5. In the embodiment,the intake manifold 3 provided on a right surface of a cylinder head 2is formed integrally with the cylinder head 2. The exhaust manifold 4 isprovided on a left surface of the cylinder head 2. The cylinder head 2is mounted on a cylinder block 6 in which the crankshaft 5 and a piston(not shown) are disposed. The cylinder block 6 pivotally supports thecrankshaft 5 such that the crankshaft 5 is rotatable.

The crankshaft 5 has its front and rear distal ends protruding fromfront and rear surfaces of the cylinder block 6. The flywheel housing 7is fixed to one side portion of the diesel engine 1 (in the embodiment,a front surface side of the cylinder block 6) intersecting thecrankshaft 5. A flywheel 8 is disposed in the flywheel housing 7. Theflywheel 8, which is pivotally supported on the front end side of thecrankshaft 5, is configured to rotate integrally with the crankshaft 5.The flywheel 8 is configured such that power of the diesel engine 1 isextracted to an actuating part of a work machine (for example, ahydraulic shovel, a forklift, or the like) through the flywheel 8. Thecooling fan 9 is disposed in the other side portion of the diesel engine1 (in the embodiment, a rear surface side of the cylinder block 6)intersecting the crankshaft 5. A rotational force is transmitted fromthe rear end side of the crankshaft 5 to the cooling fan 9 through aV-belt 10.

An oil pan 11 is disposed on a lower surface of the cylinder block 6. Alubricant is stored in the oil pan 11. The lubricant in the oil pan 11is suctioned by an oil pump 12 (see FIG. 11 ) disposed on the rightsurface side of the cylinder block 6, the oil pump 12 being arranged ina coupling portion where the cylinder block 6 is coupled to the flywheelhousing 7. The lubricant is then supplied to lubrication parts of thediesel engine 1 through an oil cooler 13 and an oil filter 14 that aredisposed on the right surface of the cylinder block 6. The lubricantsupplied to the lubrication parts is then returned to the oil pan 11.The oil pump 12 is configured to be driven by rotation of the crankshaft5.

In the coupling portion where the cylinder block 6 is coupled to theflywheel housing 7, a fuel feed pump 15 for feeding a fuel is attached.The fuel feed pump 15 is disposed below an EGR device 24. A common rail16 is fixed to a side surface of the cylinder block 6 at a locationbelow the intake manifold 3 of the cylinder head 2. The common rail 16is disposed above the fuel feed pump 15. Injectors (not shown) for fourcylinders are provided on an upper surface of the cylinder head 2 whichis covered with a head cover 18. Each of the injectors has a fuelinjection valve of electromagnetic-controlled type.

Each of the injectors is connected to a fuel tank (not shown) throughthe fuel feed pump 15 and the common rail 16 having a cylindrical shape.The fuel tank is mounted in a work vehicle. A fuel in the fuel tank ispressure-fed from the fuel feed pump 15 to the common rail 16, so that ahigh-pressure fuel is stored in the common rail 16. By controlling theopening/closing of the fuel injection valves of the injectors, thehigh-pressure fuel in the common rail 16 is injected from the injectorsto the respective cylinders of the diesel engine 1.

A blow-by gas recirculation device 19 is provided on an upper surface ofthe head cover 18 covering intake and exhaust valves (not shown), etc.disposed on the upper surface of the cylinder head 2. The blow-by gasrecirculation device 19 takes in a blow-by gas that has leaked out of acombustion chamber of the diesel engine 1 or the like toward the uppersurface of the cylinder head 2. A blow-by gas outlet of the blow-by gasrecirculation device 19 is in communication with an intake part of atwo-stage turbocharger 30 through a recirculation hose 68. A blow-bygas, from which a lubricant component is removed in the blow-by gasrecirculation device 19, is then recirculated to the intake manifold 3via the two-stage turbocharger 30.

An engine starting starter 20 is attached to the flywheel housing 7. Thestarter 20 is disposed below the exhaust manifold 4. A position wherethe starter 20 is attached to the flywheel housing 7 is below a couplingportion where the cylinder block 6 is coupled to the flywheel housing 7.

A coolant pump 21 for circulating a coolant is provided in a portion ofthe rear surface of the cylinder block 6, the portion being a littleleft-hand. Rotation of the crankshaft 5 causes the coolant pump 21 aswell as the cooling fan 9 to be driven through the cooling fan drivingV-belt 10. Driving the coolant pump 21 causes a coolant in a radiator(not shown) mounted in the work vehicle to be supplied to the coolantpump 21. The coolant is then supplied to the cylinder head 2 and thecylinder block 6, to cool the diesel engine 1.

A coolant inlet pipe 22 disposed below the exhaust manifold 4 isprovided on the left surface of the cylinder block 6 and is fixed at aheight equal to the height of the coolant pump 21. The coolant inletpipe 22 is in communication with a coolant outlet of the radiator. Acoolant outlet pipe 23 that is in communication with a coolant inlet ofthe radiator is fixed to a rear portion of the cylinder head 2. Thecylinder head 2 has a coolant drainage 35 that protrudes rearward fromthe intake manifold 3. The coolant outlet pipe 23 is provided on anupper surface of the coolant drainage 35.

The inlet side of the intake manifold 3 is coupled to an air cleaner(not shown) via a collector 25 of an EGR device 24 (exhaust-gasrecirculation device) which will be described later. Fresh air (outsideair) suctioned by the air cleaner is subjected to dust removal andpurification in the air cleaner, then fed to the intake manifold 3through the collector 25, and then supplied to the respective cylindersof the diesel engine 1. In the embodiment, the collector 25 of the EGRdevice 24 is coupled to the right side of the intake manifold 3 which isformed integrally with the cylinder head 2 to form the right surface ofthe cylinder head 2. That is, an outlet opening of the collector 25 ofthe EGR device 24 is coupled to an inlet opening of the intake manifold3 provided on the right surface of the cylinder head 2. In thisembodiment, the collector 25 of the EGR device 24 is coupled to the aircleaner via an intercooler (not shown) and the two-stage turbocharger30, as will be described later.

The EGR device 24 includes: the collector 25 serving as a relay pipepassage that mixes a recirculation exhaust gas of the diesel engine 1(an EGR gas from the exhaust manifold 4) with fresh air (outside airfrom the air cleaner), and supplies a mixed gas to the intake manifold3; an intake throttle member 26 that communicates the collector 25 withthe air cleaner; a recirculation exhaust gas tube 28 that constitutes apart of a recirculation flow pipe passage connected to the exhaustmanifold 4 via an EGR cooler 27; and an EGR valve member 29 thatcommunicates the collector 25 with the recirculation exhaust gas tube28.

The EGR device 24 is disposed on the right lateral side of the intakemanifold 3 in the cylinder head 2. The EGR device 24 is fixed to theright surface of the cylinder head 2, and is in communication with theintake manifold 3 in the cylinder head 2. In the EGR device 24, thecollector 25 is coupled to the intake manifold 3 on the right surface ofthe cylinder head 2, and an EGR gas inlet of the recirculation exhaustgas tube 28 is coupled and fixed to a front portion of the intakemanifold 3 on the right surface of the cylinder head 2. The EGR valvemember 29 and the intake throttle member 26 are coupled to the front andrear of the collector 25, respectively. An EGR gas outlet of therecirculation exhaust gas tube 28 is coupled to the rear end of the EGRvalve member 29.

The EGR cooler 27 is fixed to the front surface of the cylinder head 2.The coolant and the EGR gas flowing in the cylinder head 2 flows intoand out of the EGR cooler 27. In the EGR cooler 27, the EGR gas iscooled. EGR cooler coupling bases 33, 34 for coupling the EGR cooler 27to the front surface of the cylinder head 2 protrude from left and rightportions of the front surface of the cylinder head 2. The EGR cooler 27is coupled to the coupling bases 33, 34. That is, the EGR cooler 27 isdisposed on the front side of the cylinder head 2 and at a positionabove the flywheel housing 7 such that a rear end surface of the EGRcooler 27 and the front surface of the cylinder head 2 are spaced fromeach other.

The two-stage turbocharger 30 is disposed on a lateral side (in theembodiment, the left lateral side) of the exhaust manifold 4. Thetwo-stage turbocharger 30 includes a high-pressure turbocharger 51 and alow-pressure turbocharger 52. The high-pressure turbocharger 51 includesa high-pressure turbine 53 in which a turbine wheel (not shown) isprovided and a high-pressure compressor 54 in which a blower wheel (notshown) is provided. The low-pressure turbocharger 52 includes alow-pressure turbine 55 in which a turbine wheel (not shown) is providedand a low-pressure compressor 56 in which a blower wheel (not shown) isprovided.

An exhaust gas inlet 57 of the high-pressure turbine 53 is coupled tothe exhaust manifold 4. An exhaust gas inlet 60 of the low-pressureturbine 55 is coupled to an exhaust gas outlet 58 of the high-pressureturbine 53 via a high-pressure exhaust gas tube 59. An exhaust gasintroduction side end portion of an exhaust gas discharge pipe (notshown) is coupled to an exhaust gas outlet 61 of the low-pressureturbine 55. A fresh air supply side (fresh air outlet side) of the aircleaner (not shown) is connected to a fresh air inlet port (fresh airinlet) 63 of the low-pressure compressor 56 via an air supply pipe 62. Afresh air inlet port 66 of the high-pressure compressor 54 is coupled toa fresh air supply port (fresh air outlet) 64 of the low-pressurecompressor 56 via a low-pressure fresh air passage pipe 65. A fresh airintroduction side of the intercooler (not shown) is connected to a freshair supply port 67 of the high-pressure compressor 54 via ahigh-pressure fresh air passage pipe (not shown).

The high-pressure turbocharger 51 is coupled to the exhaust gas outlet58 of the exhaust manifold 4, and is fixed to the left lateral side ofthe exhaust manifold 4. On the other hand, the low-pressure turbocharger52 is coupled to the high-pressure turbocharger 51 via the high-pressureexhaust gas tube 59 and the low-pressure fresh air passage pipe 65, andis fixed above the exhaust manifold 4. Thus, the exhaust manifold 4 andthe high-pressure turbocharger 51 with a small diameter are disposedside-by-side with respect to the left-right direction below thelow-pressure turbocharger 52 with a large diameter. As a result, thetwo-stage turbocharger 30 is arranged so as to surround the left surfaceand the upper surface of the exhaust manifold 4. That is, the exhaustmanifold 4 and the two-stage turbocharger 30 are arranged so as to forma rectangular shape in a rear view (or front view), and are compactlyfixed to the left surface of the cylinder head 2.

Next, referring to FIG. 9 to FIG. 13 , a configuration of the cylinderblock 6 will be described. The cylinder block 6 is provided with a lefthousing bracket portion 304 and a right housing bracket portion 305(protruding portions) that are disposed in end portions of a leftsurface 301 and a right surface 302 of the cylinder block 6, the endportions being on the front surface 303 side and extending in adirection along a crankshaft center 300. The flywheel housing 7 is fixedto the left housing bracket portion 304 and the right housing bracketportion 305 with a plurality of bolts. A left-side first reinforcing rib306, a left-side second reinforcing rib 307, a left-side thirdreinforcing rib 308, and a left-side fourth reinforcing rib 309, whichare arranged in this order from up to down (from the top deck side tothe oil pan rail side), are provided between the left housing bracketportion 304 and a side wall of the left surface 301. A right-side firstreinforcing rib 310 and a right-side second reinforcing rib 311, whichare arranged in this order from up to down, are disposed between theright housing bracket portion 305 and the side wall of the right surface302. The housing bracket portions 304, 305 and the reinforcing ribs 306to 311 are formed integrally with the cylinder block 6.

Each of the reinforcing ribs 306 to 311 extends in the direction alongthe crankshaft center 300. In a plan view, each of the housing bracketportions 304, 305 has a substantially wide triangular shape. Theleft-side reinforcing ribs 307, 308, 309 and the right-side secondreinforcing rib 311 have linear portions 307 a, 308 a, 309 a, 311 a thatextend from the substantially triangular portions toward a rear surface312 of the cylinder block 6 (see FIG. 7 and FIG. 8 , too). Thereinforcing ribs 306, 307, 308 are disposed in a cylinder portion of thecylinder block 6. The reinforcing ribs 309, 310, 311 are disposed in askirt portion of the cylinder block 6.

Each of the left surface 301 and the right surface 302 is provided withtwo mount attachment pedestals 317 for attachment of an engine mountwhich couples the engine 1 to a vehicle body. The two mount attachmentpedestals 317 are arranged one behind the other with respect to thefront-rear direction, and protrude at positions close to the oil panrail. The left-side fourth reinforcing rib 309 is coupled to the twomount attachment pedestals 317 protruding from the left surface 301. Theright-side second reinforcing rib 311 is coupled to the two mountattachment pedestals 317 protruding from the right surface 302. As shownin FIG. 2 , a crank case covering member 326 is secured to the rearsurface 312 of the cylinder block 6 with bolts. The crank case coveringmember 326 covers surroundings of the crankshaft 5 so as not to exposethe inside of a crank case to the outside of the engine 1. The oil pan11 is fastened to a lower surface of the crank case covering member 326with at least one bolt.

The housing bracket portions 304, 305 and the reinforcing ribs 306 to311 which are formed integrally with the cylinder block 6 contribute toenhancement of the rigidity of the cylinder block 6, and particularlythe rigidity and strength of a portion of the cylinder block 6 near thefront surface 303. Thus, vibration and noise of the engine 1 can bereduced. In addition, since the housing bracket portions 304, 305 andthe reinforcing ribs 306 to 311 contribute to an increase in a surfacearea of the cylinder block 6, the cooling efficiency of the cylinderblock 6 can be enhanced, and therefore the cooling efficiency of theengine 1 can be enhanced.

A coolant pump attaching part 319 and an inlet pipe attachment pedestal320 are provided so as to protrude from a portion of the left surface301 of the cylinder block 6, the portion being relatively close to therear surface 312. To the coolant pump attaching part 319, a coolant pump21 (see FIG. 2 , etc.) is attached. To the inlet pipe attachmentpedestal 320, the coolant inlet pipe 22 (see FIG. 3 , etc.) is attached.A portion of the inlet pipe attachment pedestal 320 close to the rearsurface 312 is coupled to the coolant pump attaching part 319. Thecoolant pump attaching part 319 and the inlet pipe attachment pedestal320 protrude in a direction away from the crankshaft 5, and contributesto enhancing of the rigidity, the strength, and the cooling efficiencyof the cylinder block 6.

A camshaft casing 314 (see FIG. 13 ) for accommodating a camshaft 313 isprovided inside the cylinder block 6. Although details are omitted, acrank gear 331 fixed to the crankshaft 5 and a cam gear 332 fixed to thecamshaft 313 are disposed on the front surface 303 of the cylinder block6. The cam gear 332 and the camshaft 313 are rotated in conjunction withthe crank gear 331. Driving a valve mechanism (not shown) that isassociated with the camshaft 313 causes an intake valve and an exhaustvalve (not shown) of the engine 1 to be opened or closed. The engine 1of this embodiment has a so-called overhead valve system.

The camshaft casing 314 is disposed in the cylinder portion of thecylinder block 6, and is arranged at a position relatively close to theleft surface 301. The camshaft 313 and the camshaft casing 314 aredisposed in the direction along the crankshaft center 300. Substantiallytriangular portions and the linear portions 307 a, 308 a of theleft-side second reinforcing rib 307 and the left-side third reinforcingrib 308 provided on the left surface 301 of the cylinder block 6 arearranged close to a position where the camshaft casing 314 is disposedin a side view, and more specifically at a position overlapping theposition where the camshaft casing 314 is disposed.

This embodiment, in which the rigidity of the camshaft casing 314 andtherearound is enhanced by the left-side second reinforcing rib 307 andthe left-side third reinforcing rib 308, can prevent distortion of thecamshaft casing 314. Accordingly, a variation in the rotation resistanceand the rotational friction of the camshaft 313, which may occur due todistortion of the camshaft casing 314, can be prevented, so that thecamshaft 313 can be rotated appropriately to open or close the intakevalve and the exhaust valve (not shown) appropriately.

Of a lubricant passage provided in the cylinder block 6, a part isdisposed in the skirt portion of the cylinder block 6 and arranged at aposition relatively close to the right surface 302. The part includes alubricant sucking passage 315 and a lubricant supply passage 316. Thelubricant supply passage 316 is disposed in the skirt portion of thecylinder block 6 and arranged at a position relatively close to thecylinder portion. The lubricant sucking passage 315 is arranged at aposition relatively close to the oil pan rail as compared to thelubricant supply passage 316.

One end of the lubricant sucking passage 315 is opened in an oil panrail lower surface (a surface opposed to the oil pan 11) of the cylinderblock 6, and is connected to a lubricant sucking pipe (not shown)disposed in the oil pan 11. The other end of the lubricant suckingpassage 315 is opened in the front surface 303 of the cylinder block 6,and is connected to a suction port of the oil pump 12 (see FIG. 11 )fixed to the front surface 303. One end of the lubricant supply passage316 is opened in the front surface 303 of the cylinder block 6 at aposition different from the position where the lubricant sucking passage315 is opened, and is connected to an ejection port of the oil pump 12.The other end of the lubricant supply passage 316 is opened in an oilcooler attachment pedestal 318 protruding from the right surface 302 ofthe cylinder block 6, and is connected to a suction port of the oilcooler 13 (see FIG. 4 , etc.) disposed on the oil cooler attachmentpedestal 318. Not only the lubricant sucking passage 315 and thelubricant supply passage 316 but also other lubricant passages areprovided in the cylinder block 6.

On the right surface 302 of the cylinder block 6, the right-side firstreinforcing rib 310 is arranged close to the position where thelubricant supply passage 316 is arranged in a side view. Morespecifically, the right-side first reinforcing rib 310 is arranged so asto overlap the position where the lubricant supply passage 316 isarranged in a side view. The right-side second reinforcing rib 311 isarranged close to the position where the lubricant sucking passage 315is arranged in a side view. The reinforcing ribs 310, 311 and thepassages 315, 316 extend in the direction along the crankshaft center300.

In this embodiment, the cooling efficiency in the vicinity of thelubricant sucking passage 315, the oil pump 12, and the lubricant supplypassage 316 can be enhanced by the right housing bracket portion 305,the right-side first reinforcing rib 310, and the right-side secondreinforcing rib 111. In particular, the right-side first reinforcing rib310 arranged at a position overlapping the lubricant supply passage 316in a side view efficiently dissipates heat in the vicinity of thelubricant supply passage 316 to the outside. This can lower thetemperature of the lubricant flowing into the oil cooler 13, and canreduce the amount of heat exchange required of the oil cooler 13.

A gear train structure of the engine 1 will now be described withreference to FIG. 10 to FIG. 15 . A gear case 330 is provided in a spacesurrounded by the front surface 303 of the cylinder block 6, the housingbracket portions 304, 305, and the flywheel housing 7. As shown in FIG.12 and FIG. 14 , front distal end portions of the crankshaft 5 and thecamshaft 313 protrude from the front surface 303 of the cylinder block6. The crank gear 331 is secured to the front distal end portion of thecrankshaft 5. The cam gear 332 is secured to the front distal endportion of the camshaft 313. A disk-shaped camshaft pulsar 339 isfastened with bolts to a surface of the cam gear 332 on the flywheelhousing 7 side such that the camshaft pulsar 339 is rotatable integrallywith the cam gear 332.

As shown in FIG. 12 , FIG. 13 , and FIG. 15 , the fuel feed pump 15provided in the right housing bracket portion 305 of the cylinder block6 includes a fuel feed pump shaft 333 as a rotation shaft extending inparallel to the rotation axis of the crankshaft 5. The front end side ofthe fuel feed pump shaft 333 protrudes from a front surface 305 a of theright housing bracket portion 305. A fuel feed pump gear 334 is securedto a front distal end portion of the fuel feed pump shaft 333. As shownin FIG. 13 , the right housing bracket portion 305 of the cylinder block6 includes a fuel feed pump attachment pedestal 323 for arranging thefuel feed pump 15 above the right-side first reinforcing rib 310. A fuelfeed pump gear 334 is secured to a front distal end portion of the fuelfeed pump shaft 333.

As shown in FIG. 11 and FIG. 12 , the oil pump 12, which is disposed onthe front surface 305 a of the right housing bracket portion 305 andarranged below the fuel feed pump gear 334, includes an oil pump shaft335 as a rotation shaft extending in parallel to the rotation axis ofthe crankshaft 5. An oil pump gear 336 is secured to a front distal endportion of the oil pump shaft 335.

On the front surface 303 of the cylinder block 6, an idle shaft 337extending in parallel to the rotation axis of the crankshaft 5 isprovided in a portion surrounded by the crankshaft 5, the camshaft 313,the fuel feed pump shaft 333, and the oil pump shaft 335. The idle shaft337 is fixed to the front surface 303 of the cylinder block 6. An idlegear 338 is rotatably supported on the idle shaft 337.

The idle gear 338 is meshed with four gears, namely, the crank gear 331,the cam gear 332, the fuel feed pump gear 334, and the oil pump gear336. Rotational power of the crankshaft 5 is transmitted from the crankgear 331 to the three gears of the cam gear 332, the fuel feed pump gear334, and the oil pump gear 336, via the idle gear 338. Thus, thecamshaft 313, the fuel feed pump shaft 333, and the oil pump shaft 335are rotated in conjunction with the crankshaft 5. In the embodiment, thegear ratio among the gears 331, 332, 334, 336, 338 is set such that: tworotations of the crankshaft 5 correspond to one rotation of the camshaft313; and one rotation of the crankshaft 5 corresponds to one rotation ofthe fuel feed pump shaft 333 and the oil pump shaft 335.

In this configuration, rotating the cam gear 332 and the camshaft 313 inconjunction with the crank gear 331 which rotates together with thecrankshaft 5 to drive the valve mechanism (not shown) that is associatedwith the camshaft 313 causes the intake valve and the exhaust valve (notshown) provided in the cylinder head 2 to be opened or closed. Inaddition, rotating the fuel feed pump gear 334 and the fuel feed pumpshaft 333 in conjunction with the crank gear 331 to drive the fuel feedpump 15 causes the fuel in the fuel tank 118 to be pressure-fed to thecommon rail 120 so that a high-pressure fuel is stored in the commonrail 120. In addition, rotating the oil pump gear 336 and the oil pumpshaft 335 in conjunction with the crank gear 331 to drive the oil pump12 causes the lubricant in the oil pan 11 to be supplied to varioussliding component parts and the like through a lubricating systemcircuit (details are not shown) including the lubricant sucking passage315, the lubricant supply passage 316, the oil cooler 13, the oil filter14, and the like. A fuel in the fuel tank 118 is pressure-fed from thefuel feed pump 15 to the common rail 16, so that a high-pressure fuel isstored in the common rail 16.

As shown in FIG. 15 , the fuel feed pump 15 serving as an auxiliarymachine that is operated in conjunction with rotation of the crankshaft5 is secured with bolts to the fuel feed pump attachment pedestal 323 ofthe right housing bracket portion 305. The right-side first reinforcingrib 310 is arranged close to the fuel feed pump attachment pedestal 323.The right-side first reinforcing rib 310 is arranged directly under thefuel feed pump 15, and the right-side second reinforcing rib 311 isarranged directly under the right-side first reinforcing rib 310. Thereinforcing ribs 310, 311 can enhance the rigidity of the fuel feed pumpattachment pedestal 323, and also can prevent the fuel feed pump 15 frombeing contacted by a foreign object such as muddy water or stone comingfrom below, for protection of the fuel feed pump 15.

The gear case 330 that accommodates the gear train and the structure ofthe flywheel housing 7 will now be described with reference to FIG. 10to FIG. 12 , FIG. 14 , and FIG. 16 to FIG. 20 . As shown in FIG. 12 andFIG. 14 , a block-side projecting portion 321 that extends along aperipheral edge of a region including the front surfaces 303, 304 a, 305a of the cylinder block 6 and of the left and right housing bracketportions 304, 305 is provided upright on a peripheral edge portion ofthe front surfaces 303, 304 a, 305 a. The block-side projecting portion321 is joined with the flywheel housing 7. The block-side projectingportion 321 is joined with the flywheel housing 7. The block-sideprojecting portion 321 has a cutout portion 321 a at a location betweenthe left and right oil pan rails of the cylinder block 6. A spacebetween an end surface of the block-side projecting portion 321 and thefront surfaces 303, 304 a, 305 a in a side view defines a block-sidegear casing 322.

As shown in FIG. 14 and FIG. 16 to FIG. 20 , the flywheel housing 7which is made of, for example, cast iron includes a flywheelaccommodating part 401 that accommodates the flywheel 8. The flywheelaccommodating part 401 has a bottomed cylindrical shape formed by acircumferential wall surface portion 402 and a rear wall surface portion403 being coupled to each other. The circumferential wall surfaceportion 402 has a substantially cylindrical shape and covers the outercircumferential side of the flywheel 8. The rear wall surface portion403 covers a rear surface side (a surface on the cylinder block 6 side)of the flywheel 8. The flywheel 8 is accommodated in a space surroundedby the circumferential wall surface portion 402 and the rear wallsurface portion 403. The circumferential wall surface portion 402 is inthe shape of a substantially truncated cone with its radius decreasingtoward the rear wall surface portion 403. The rear wall surface portion403 has, in its central portion, a crankshaft insertion hole 404 throughwhich the crankshaft 5 is inserted.

A flange-side projecting portion 405 having an annular shape thatcorresponds to the shape of the block-side projecting portion 321 of thecylinder block 6 is coupled to the rear wall surface portion 403 so asto surround a position where the crankshaft insertion hole 404 isdisposed. The center of the flange-side projecting portion 405 isdeviated upward from the crankshaft insertion hole 404. A lower portionof the flange-side projecting portion 405, which extends in theleft-right direction (lateral direction), is close to the crankshaftinsertion hole 404 and is coupled to the rear wall surface portion 403.

Upper, left, and right portions of the flange-side projecting portion405 are located outside the rear wall surface portion 403. A frontportion of the circumferential wall surface portion 402 and a frontportion of the flange-side projecting portion 405 located outside therear wall surface portion 403 are coupled to each other in an outer wallportion 406. The outer wall portion 406 has a curved slope shapeconvexing in a direction away from the crankshaft 5. In the flywheelhousing 7, a lower portion of the flywheel accommodating part 401protrudes from the flange-side projecting portion 405 in a directionaway from the crankshaft 5.

A space between the rear wall surface portion 403 and an end surface ofthe flange-side projecting portion 405 in a side view defines ahousing-side gear casing 407. This flange-side gear casing 407 and theabove-mentioned block-side gear casing 322 constitute the gear case 330.With the engine 1 of this embodiment, the flywheel 8 and the gear traincan be arranged on the same end portion of the crankshaft 5. Twist ofthe crankshaft 5 can be reduced by solving the twist of crankshaft 5caused by the structure having the flywheel 8 and the gear trainarranged across from each other over the cylinder block 6. Further,regarding torsion vibration of the crankshaft 5 which causes vibrationand noise of the gear train, the torsion vibration of the crankshaft 5to be transmitted to the gear train is reduced by arranging the flywheel8 and the gear train having a large moment of inertia, on the same endportion of the crankshaft 5. This way, vibration and noise of the geartrain can be reduced. Further, the number of parts can be reduced ascompared to a case of using a separate part for the gear case. Hence,reduction of the manufacturing costs and assembling processes can beachieved.

Further, the gear case 330 is structured by the cylinder block 6 and theflywheel housing 7 of cast iron, for example. The left and right housingbracket portions 304, 305 structuring the gear case 330 and thereinforcing ribs 306 to 311 reinforcing these members are integrallyformed with the cylinder block 6. Therefore, the rigidity is improved ascompared to a traditional gear case made of aluminum die-cast, andvibration and noise of the gear train are reduced. Further, the noisegenerated from the cylinder block 6 and the gear train can be attenuatedby the weight-reduction space 408 continuous with the gear case 330, andthe outer wall portion 406 is formed in a curved inclined shape, so thatthe radiation area is reduced as compared with the rectangularparallelepiped shape. Therefore, the noise emitted to the outside of theengine can be reduced.

Inside the flywheel housing 7, a weight-reduction space 408 is formedbetween an outer wall of the circumferential wall surface portion 402 ofthe flywheel accommodating part 401 and an inner wall of the outer wallportion 406. A plurality of housing ribs 409 (ribs) configured to couplethe circumferential wall surface portion 402 to the outer wall portion406 are disposed in the weight-reduction space 408. In this way, whilethe weight of the flywheel housing 7 is reduced by the weight-reductionspace 408, the housing ribs 409 achieve the strength. Thus, problemssuch as an increase in weight, manufacturing defects during casting,cracks due to concentration of stress taking place when the thickness ofa wall is increased to achieve the strength of the flywheel housing canbe avoided.

As shown in FIG. 18 , by forming the circumferential wall surfaceportion 402 in a shape of a substantially truncated cone with its radiusdecreasing towards the cylinder block 6. This way, the circumferentialwall surface portion 402 exposed to the weight-reduction space 408 has aslope that is inclined by an angle θ1 so that its side of the cylinderblock 6 is lowered relative to the crankshaft center 300. Further, asshown in FIG. 19 and FIG. 20 , a surface of each housing rib 409 on theside of the block upper surface 341 (cylinder head coupling surface) ofthe cylinder block 6 has a slop inclined by an angle of θ2 so as to bein a position closer to the side of the block upper surface 341 (seeFIG. 12 ) with an increase in the distance from the cylinder block 6.This way, accumulation of lubricating oil in the flywheel housing 7 isprevented, and an accurate amount of lubricating oil in the engine 1 canbe observed. It should be noted that the angles θ1 and 02 may be thesame or may be different from each other. Further, the angles θ2 of theplurality of housing ribs 409 may be the same or may be different fromone another.

As shown in FIG. 15 , FIG. 16 , and FIG. 20 to FIG. 21 , the flywheelhousing 7 has a sensor attachment seating 414 for a crankshaft rotationangle sensor 413 (crankshaft rotation angle detecting member) configuredto detect a rotation angle of the crankshaft 5. The sensor attachmentseating 414 has a through hole 415 to which the crankshaft rotationangle sensor 413 is inserted. An annular crankshaft pulsar 502 (see FIG.14 ) are fixed to the outer circumferential side of the flywheel 8. Onthe outer peripheral surface of the crankshaft pulsar 502, outputprotrusions are formed as detectable portions arranged at predeterminedcrank angles (rotation angles). On the outer peripheral surface of thecrankshaft pulsar 502, for example, a tooth-chipped part is formed at aportion corresponding to the top dead center (TDC) of the first orfourth cylinder. The crankshaft rotational angle sensor 413 isdetachably mounted on the sensor mounting seat 414 and is arranged closeto the outer circumferential side of the crankshaft pulsar 502 so as toface the crankshaft pulsar 502. The crankshaft rotation angle sensor 413is for detecting the crank angle (rotation angle) of the crankshaft 5,and each of the output protrusions of the crankshaft pulsar 502 passesits vicinity with rotation of the crankshaft 5, thereby outputting acrank angle signal.

Further, the flywheel housing 7 has a sensor attachment seating 417 fora camshaft rotation angle sensor 416 (drive gear rotation angledetecting member) configured to detect a rotation angle of the cam gear332. The sensor attachment seating 417 has a through hole 418 to whichthe camshaft rotation angle sensor 416 is inserted. The camshaftrotation angle sensor 416 is detachably mounted on the sensor mountingseat 417 and is arranged close to the outer circumferential side of thecamshaft pulsar 339 so as to face the camshaft pulsar 339 bolt-fastenedto the cam gear 332. On the outer peripheral surface of the camshaftpulsar 339, output protrusions are formed as detectable portionsarranged at every 90 degrees (every 180 degree crank angle). Extra toothis formed immediately before each of the output protrusions (on theupstream side of the rotation) corresponding to, for example, the topdead center of the first cylinder on the circumferential surface of thecamshaft pulsar 339. The camshaft rotation angle sensor 416 is fordetecting the rotation angle of the camshaft 313 (which may be referredto as a cam gear 332) of the camshaft, and each of the outputprotrusions and the extra tooth of the camshaft pulsar 339 passes itsvicinity with rotation of the camshaft 313, thereby outputting arotation angle signal.

A crank angle signal output from the crankshaft rotation angle sensor413 with the rotation of the crankshaft 5 and a rotation angle signaloutput from the camshaft rotation angle sensor 416 with the rotation ofthe camshaft 313 are transmitted to a controller (not shown). Thecontroller discriminates the cylinder and calculates the crank anglefrom these signals, and electronically controls each fuel injectionvalve (not shown) (controls fuel injection and ignition for eachcylinder) based on the calculation result. An injection pressure, aninjection timing, and an injection period (injection amount) of the fuelsupplied from each injector (not shown) can be controlled with a highaccuracy.

In this embodiment, the flywheel housing 7 structured as a single parthas the sensor attachment seating 414 for the crankshaft rotation anglesensor 413 configured to detect the rotation angle of the crankshaft 5and the sensor attachment seating 417 for the camshaft rotation anglesensor 416 configured to detect the rotation angle of the camshaft 313(cam gear 332). With this, an attachment error caused by unevenness inthe manufacturing accuracy and the assembling accuracy, which takesplace at a time of attaching the two rotation angle sensors 413, 416 toseparate parts as in a traditional art, can be eliminated. Byeliminating the error, discrimination of the cylinder and phasecalculation of the rotation angle of the crankshaft 5 can be accuratelyperformed. Hence, the exhaust gas performance and the like can beprevented from being deteriorated. Further, by mounting two rotationangle sensors 413, 416 to the flywheel housing 7 which is a single part,the distance between the rotation angle sensors 413, 416 is shortened ascompared with a traditional art in which these rotation angle sensors413 and 416 are disposed with the cylinder block 6 interposedtherebetween. Therefore, arrangement of harnesses connected to therotation angle sensors 413, 416 can be simplified. Further, bystandardizing the shape of the sensor mounting seats 414, 417, the costsof attaching parts for the rotation angle sensors 413, 416 to the sensormounting seats 414, 417 can be reduced.

A pump shaft pulsar may be mounted to the fuel feed pump gear 334,instead of the camshaft pulsar 339 and the camshaft rotation anglesensor 416. Further, the drive gear rotation angle detecting memberconfigured to detect the rotation angle of the fuel feed pump shaft 333(fuel feed pump gear 334) may be mounted to the flywheel housing 7. Astructure of discriminating cylinder by using a pump shaft pulsar isdisclosed in PTL 2, for example.

As shown in FIG. 16 , FIG. 17 , FIG. 19 , and FIG. 22 , a portion wherethe lubricating oil supply port 419 is formed projects from the upperright portion of the outer wall portion 406 of the flywheel housing 7.The lubricant oil supply port 419 has a substantially cylindricalthrough hole penetrating the outer wall portion 406. The opening on theexternal side of the lubricating oil supply port 419 is formed along aplane roughly perpendicular to the central axis in a substantiallycylindrical shape. An opening on the internal side of the lubricant oilfiller port 419 is formed along the inner wall of the outer wall portion406 having a convex curved inclined shape in a direction away from thecrankshaft 5. Thus, the lubricating oil supply port 419 is such that theopening area of the internal side is greater than the opening area ofthe external side.

As shown in FIG. 22 , the lubricating oil supply port 419 is configuredso that a meshing position of the fuel feed pump gear 334 and the idlinggear 338 is visually observable from outside. Therefore, the timingmarks on the fuel feed pump gear 334 and the idling gear 338 to beadjusted with the phase of the crankshaft 5 can be observed through thelubricating oil supply port 419. With this, the fuel feed pump 15 can bereplaced, adjusting the timing marks, without detaching the flywheel 8and the flywheel housing 7 which are very heavy parts. The number ofparts to be replaced and the number of processes for attaching anddetaching the engine 1 can be reduced, and the service performance canbe significantly improved. Further, since the flywheel 8 which is arotating member does not have to be detached, the product safety afterthe maintenance can be improved. Further, since an audit windowexclusively for mark adjustment does not have to be provided in theflywheel housing 7, an opening portion area of the flywheel housing 7including the gear case 330 can be reduced. Therefore, gear noiseleaking to the outside the engine 1 can be suppressed.

Further, the lubricating oil supply port 419 is such that an openingarea of an internal side of the flywheel housing is greater than anopening area of an external side of the flywheel housing 7. Therefore,the field of view for visually observing the inside of the gear casethrough the lubricating oil supply port 419 can be broadened, thusimproving the convenience in the work of adjusting the mark at the timeof replacing the fuel feed pump 15. Further, with the opening area ofthe internal side being greater than the opening area of the externalside, spilling of lubricating oil at a time of supplying the lubricatingoil through the lubricating oil supply port 419 can be prevented. Theshape of the lubricating oil supply port 419 is not limited to acylindrical shape, and may be, for example, an inverted tapered shapewhich broadens towards the internal side of the flywheel housing 7.

In addition, the lubricant oil filler port 419 is opened so as topenetrate towards a portion sandwiched between the two housing ribs 409,through a portion of the peripheral wall surface portion 402 exposed inthe weight-reduction space 408. As a result, the lubricating oilsupplied from the lubricating oil supply port 419 is supplied to theportion of the peripheral wall surface portion 402 intersecting thehorizontal surface, and the lubricating oil does not spill over theother parts such as the camshaft rotation angle sensor 416.

As shown in FIG. 16 and FIG. 17 , the flywheel 7 has a starter attachingpart 411 having a starter attachment pedestal 410 that is flush with theflange-side projecting portion 405. The starter attachment pedestal 410is coupled to the circumferential wall surface portion 402 and theflange-side projecting portion 405 at a location outside thehousing-side projecting portion 405. The starter attaching part 411 hasa through hole 412 bored from the starter attachment pedestal 410 to theinner wall of the circumferential wall surface portion 402. The flywheelhousing 7 is fastened to the front surface 303 side of the cylinderblock 6 with bolts in thirteen bolt holes 351 (see FIG. 12 ) of theblock-side projecting portion 321 of the cylinder block 6 and in boltholes 353 (see FIG. 12 ) of two housing bolting boss portions 352 of thefront surface 303.

As shown in FIG. 10 , FIG. 12 , and FIG. 13 , the left housing bracketportion 304 of the cylinder block 6 has its peripheral edge portionrecessed toward a peripheral edge portion of the flywheel housing 7, toform a bracket recessed portion 325 having a recessed shape. While theflywheel housing 7 is fixed to the cylinder block 6, the starter 20 isdisposed to the starter attachment pedestal 410 of the flywheel housing7 which is exposed on the lower side of the bracket recessed portion325. As shown in FIG. 14 , an annular ring gear 501 for the starter 20and a crankshaft pulsar 502 are fixed to the outer circumferential sideof the flywheel 8. The ring gear 501 and the crankshaft pulsar 502 arefitted in from opposite sides in a thickness direction of the flywheel8. The starter 20 includes a pinion gear 503 (see FIG. 12 ) that isdisposed in the through hole 412 and is separatably meshed with the ringgear 501.

In the vicinity of the starter attachment pedestal 410, the flywheelhousing 7 made of cast iron is fastened with bolts to the block-sideprojecting portion 321 (see FIG. 12 and FIG. 14 ) that is providedupright on the peripheral edge portion of the front surface 304 a of theleft housing bracket portion 304. In the cylinder block 6, the left-sidefourth reinforcing rib 309 that couples the left housing bracket portion304 to the left surface 301 is disposed near the bracket recessedportion 325 of the left housing bracket portion 304 which is providednear the starter attachment pedestal 410. Thereby, the rigidity of thestarter attachment pedestal 410 and therearound is enhanced. Inaddition, the bracket recessed portion 325 of the left housing bracketportion 304 and a portion of the block-side projecting portion 321 (seeFIG. 12 ) provided on the front surface 303 and near the starterattachment pedestal 410 so as to be continuous with the bracket recessedportion 325 also enhance the rigidity of the starter attachment pedestal410 and therearound.

In this embodiment, the starter 20 can be attached to a portion given ahigh rigidity by the left-side fourth reinforcing rib 309 and the like.Thus, mispositioning and deformation of the starter 20 can be prevented,which may otherwise be caused by distortion of the starter attachmentpedestal 410 or the left housing bracket portion 304. Accordingly,breakdown of the starter 20 and poor meshing between the pinion gear ofthe starter 20 and the ring gear 501 of the flywheel 8 can be prevented.

The configurations of respective parts of the present invention are notlimited to those of the illustrated embodiment, but can be variouslychanged without departing from the gist of the invention.

REFERENCE SIGNS LIST

-   1 engine-   5 crankshaft-   6 cylinder block-   7 flywheel housing-   8 flywheel-   9 fuel feed pump-   300 crankshaft axial direction-   301 left surface (opposite side portions)-   302 right surface (opposite side portions)-   303 front surface (one side surface)-   304 left housing bracket portion-   305 right housing bracket portion-   313 camshaft-   330 gear case-   331 crank gear-   332 cam gear-   333 fuel pump shaft (pump shaft)-   334 pump gear-   338 idling gear-   341 block upper surface (cylinder head joining surface)-   402 circumferential wall surface portion-   406 outer wall portion-   408 weight-reduction space-   409 housing rib (rib)-   413 crankshaft rotation angle sensor (crankshaft rotation angle    detecting member)-   414 sensor attachment seating (attachment part)-   416 camshaft rotation angle sensor (rotation shaft rotation angle    detecting member)-   414 sensor attachment seating (attachment part)-   419 lubricating oil supply port

The invention claimed is:
 1. An engine device comprising: a flywheelhousing in which a flywheel that rotates integrally with a crankshaft isaccommodated on one side portion of a cylinder block; housing bracketportions each protruding in a direction away from the crankshaft fromeach of opposite side portions of the cylinder block extending along acrankshaft axial direction; and a gear case formed by the one sideportion, the housing bracket portions, and the flywheel housing, whereinthe gear case accommodates a gear train.
 2. The engine device accordingto claim 1, wherein in the flywheel housing, a weight-reduction spacecontinuous with the gear case is formed between a cylindricalcircumferential wall surface portion that covers an outercircumferential side of the flywheel and an outer wall portion thatcovers the outer circumferential side of the circumferential wallsurface portion, and a rib portion connecting the circumferential wallsurface portion and the outer wall portion is formed.
 3. The enginedevice according to claim 2, wherein the circumferential wall surfaceportion is formed in a substantially conical truncated shape in whichthe radius becomes smaller toward the cylinder block side, and a surfaceof the rib on a side of a cylinder head coupling surface of the cylinderblock is formed to incline so as to be in a position closer to thecylinder head coupling surface with an increase in the distance from thecylinder block.
 4. The engine device according to claim 1, wherein thegear train includes a crank gear fixed to the crankshaft, an idle gearthat meshes with the crank gear, a cam gear that is fixed to a camshaftand meshes with the idle gear, and a pump gear that is fixed to a pumpshaft of a fuel feed pump and meshes with the idle gear; and wherein theflywheel housing is formed to have an attachment part for a crankrotation angle detection member that detects a rotation angle of thecrankshaft and an attachment part for a rotation shaft rotation angledetection member that detects a rotation angle of the cam gear or thepump gear.
 5. The engine device according to claim 4, wherein alubricating oil supply port penetratingly opened in the flywheel housingis configured so that a meshing position of the fuel feed pump gear andthe idle gear is visually observable.
 6. The engine device according toclaim 5, wherein the lubricating oil supply port has an opening area ofan inner side of the flywheel housing larger than an opening area of anexterna side.